In our co-pending, commonly assigned application, Ser. No. 049,557, filed June 18, 1979, entitled "Method and Apparatus for Accelerating A Solid Mass", now U.S. Pat. No. 4,429,612, there is disclosed an apparatus for and method of accelerating masses ranging from fractions of a gram to kilograms to velocities in the range of approximately 10.sup.2 kilometers per second. The solid mass, preferably in the form of a projectile, is accelerated along a predetermined path by passing an electric discharge through a plasma layer adjacent the projectile surface layer. The discharge plasma is imploded against the projectile surface layers so the plasma arrives on a region of the peripheral projectile surface layer to impart force components to the projectile along and normal to the path, to thereby accelerate the projectile in free flight along the path. To achieve stable, free flight acceleration along the path, the plasma arrives at the region on opposite sides of the peripheral surface with substantially equal forces so the normal components are balanced and the projectile is accelerated by the axial components. The projectile region against which the forces act is a surface of revolution about a longitudinal axis of the plasma and the plasma has a circular inner imploding periphery at right angles to the axis when it arrives at the surface.
To accelerate the projectile to velocities in the stated range, the projectile must interact with the imploding plasma over a relatively long distance, such as approximately one meter to several hundreds of meters, or even greater distances if higher velocities are desired. To achieve stable acceleration over this considerable length, implosion of the plasma is synchronized with acceleration of the projectile along the path so arrival of the plasma on the peripheral projectile region is matched with movement of the projectile along the path. Preferably, the synchronism is obtained by initiating separate plasma discharges at spaced regions along the path. The discharges are timed so they are initiated at the spaced regions downstream of the projectile prior to the projectile arriving at the regions and impact on the surface of the projectile. The separate discharges may be initiated in response to a position detector for the projectile along the path.
It has been found that the method and apparatus disclosed in our previously mentioned co-pending application does not efficiently accelerate a projectile at relatively low velocities, i.e., less than 15 kilometers per second. It is, therefore, an object of the present invention to provide a new and improved apparatus for and method of accelerating a projectile from virtually at rest to a velocity that could range up to about 50 kilometers per second.
Another object of the invention is to provide a new and improved apparatus for and method of accelerating a projectile from virtually a rest condition to a velocity at which it can be efficiently accelerated by the prior art structure to a velocity in the range of 10.sup.2 kilometers per second.